Regulations and policy statements governing pediatric clinical research require that children and adolescents be offered a voice, to the extent of their capacity, in decisions about their research participation. However, data on children's and adolescents'capacity to take part in research decisions are sparse, in part because there is no validated methodology for assessing children's capacity. Thus, there is an urgent need to develop such a methodology in order to understand children's abilities, as well as to clarify their developmental psychological foundations and contextual influences. These data are necessary to inform rational policy regarding children's roles in research decisions. Improving policy and practice related to children's participation in research decisions is of special importance in pediatric oncology, due to the pervasive integration of clinical research into pediatric cancer care. In this preliminary study, we seek to validate the MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR), an instrument for assessing capacity that has been employed extensively among adults with and without cognitive or psychiatric impairment. The instrument will be administered to 100 children and adolescents ages 9-17 years. Additional sociodemographic and clinical information about the children, as well as information about families'decision making styles, will be collected by a parent survey. Using receiver operating characteristic (ROC) curves, children's scores on the 3 major subscales of the MacCAT-CR (Understanding, Appreciation and Reasoning) will be validated against judgments of capacity as determined by a 3-person expert panel. Subscale scores will also be validated against verbal cognitive ability as measured by subtests of the Wechsler Abbreviated Scale of Intelligence (WASI). Secondary aims are: 1) to describe the correlations between MacCAT-CR subscale scores and performance subtest scores of the WASI;2) to describe the correlations between MacCAT-CR subscale scores and measures assessing the development of judgment (i.e., impulsivity, future orientation);and 3) to conduct exploratory multivariate regression analyses of psychological, sociodemographic and contextual factors that influence children's capacity to make research decisions. Data from these analyses will be used to refine a conceptual model of the factors that influence children's capacity. This model, in turn, will determine the design of a subsequent comprehensive study of children's and adolescents'capacity to participate in decisions about clinical research. PUBLIC HEALTH RELEVANCE: Clinical pediatric research is essential to advancing children's health and well-being, but children's inability to give legally effective informed consent makes such research ethically challenging. By validating an instrument for assessing decision making capacity that has been widely used among adults for use with children, this research will enhance the ethical conduct of pediatric research and thereby make an important contribution to improving children's health.